The present invention relates to an improved yarn feeding drum, and more particularly to an improved yarn feeding drum with a guiding flange on its circumferential surface capable of automatically guiding the yarn or driving belt into true position for feeding the yarn.
As shown in FIG. 11, a conventional yarn feeding device includes a support body 5, a yarn feeding drum 1 freely rotatably disposed thereon, a pair of yarn guide eyes 8 mounted on a guiding frame 51. In normal positive yarn feeding operation, the yarn guiding frame 51 is located in a position indicated by solid line in FIG. 11. When the specification of the fabric is changed and the tension of the yarn needs to be adjusted or the yarn feeding conditions need to be changed and thus a trial run is required, or in a negative irregular yarn feeding operation, the yarn guiding frame 51 is necessary to be operated downward to a position indicated by phantom line in FIG. 11, so as to prevent the yarn from being pressed by the driving belt 2. Otherwise, in general positive yarn feeding operation, the yarn is rarely not pressed by the driving belt.
However, in case the yarn wound on tapered cone or tube is poor or the yarn outgoing resistance is relatively great, the yarn will be abnormally fed in an intermittently shaking manner. On the other hand, when a rough count yarn with larger weight is fed, a greater rotary inertia is created under high speed yarn feeding operation, as a result, the yarn is unable to be sufficiently pressed by the driving belt on the circumferential surface of the drum and is likely to slip away from the pressing -area of the driving belt, so that the high and low yarn tension will alternate and sometimes the yarn will even drop from the lower edge of the driving belt and become released from the pressing of the driving belt. Such abnormal yarn feeding operation will cause defects or even breakages of the fabrics and thus waste the same.
Moreover, the positive yarn feeding operations of general yarn feeding drums are almost designed for fine count yarn, in which the frictional coefficients of the driving belt and the circumferential surface of the yarn feeding drum and the pressing force exterted on the yarn are constant. However, in case an open end rough count yarn feeding operation is alternatively performed, because the rough count yarn has a less flexibility than a ring fine count yarn and has a weight much greater than the ring fine count yarn, under the same operation conditions, the rough count yarn is likely to drop from the lower edge of belt and escape from being pressed by the belt as shown in FIG. 11. As a consequence, the quality of the resultant fabric is poor and unsatisfactory. In addition, although the pressing position and pressing angle of the driving belt 2 on the yarn feeding drum can be adjusted by means of adjusting the adjusting screws 6 and 7 (referring to FIG. 11), in case the adjusting screws 6 and 7 are loosened due to the vibration the yarn feeding device, the driving belt will displace from the normal pressing position and angle and abnormally move up and down. As a result, the yarn feeding tension will become extremely unstable and if the operator fails to secure the screws in time, great amount of fabric with ununified quality will be produced to cause great loss.